A pulsed laser Raman technique for biological applications has been under development. Under resonance conditions the backscattering geometry was found superior to the commonly used 90 degrees configuation. Because of the "saturation" or "bleaching" effect by high power laser pulses (the no. of photons in each pulse exceeds the no. of of molecules in the scattering volume) spurious excition profile can often be generated. This difficulty may be overcome by the so called "180 degrees scattering" technique using a cylindrical lens. Interpretations of the detailed resonance Raman excitation profiles of Ni(II)Etio and Cr(III)TPPC1 have been given (J. Chem. Phys. 66, 3387 (1977)). Within the crude Born-Oppenheimer approximation, a theoretical model is presented which explains the O-O enhancements of depolarized modes as arising from interference of intermanifold (Q-B) and intramanifold (Q-Q) vibronic coupling. Comparison of the computed and observed excitation profiles shows that a Jahn-Teller distortion is present in the Q state. BIBLIOGRAPHIC REFERENCES: Nai-Teng Yu, Emily J. East, Robert C.C. Chang and J.F.R. Kuck, Jr., Raman Spectra of Bird and Reptile Lens Protein", Exp. Eye Res. 24, 321-334 (1977). Nai-Teng Yu, "Raman Spectroscopy: A Conformational Probe in Biochemistry", CRC Critical Rev. in Biochemistry, 4, 229-280 (1977).